Pedicure prosthesis for the metatarsal arch of the foot

ABSTRACT

A support for the metatarsal arch of the foot is formed by injection of a self-curing non-foamable fluid material into the arch support enclosure. This fluid material automatically cures into a rigid support or prosthesis for the arch of the foot. This polymerizable material is normally contained in either a insert under the foot or by a balloon like material, in either case the polymerizable material is pumped or injected into the resulting enclosure. The same method can be used to form in situ prosthesis casts for any part of the body, i.e., to form splints, braces, etc., contured directly to the portion of the human body for which it is designed to lend support. The self-curing material is preferably a cross-linkable prepolymerized material which includes an initiator, and the self-curing is achieved by the application of mild temperatures, e.g., 120* F.

United States Patent 1191 Johnson 1 1 Jan. 1, 19741 1 PEDICUREPROSTHESIS FOR THE METATARSAL ARCH OF THE FOOT 22 Filed: July 23,1971

211 Appl.No.: 165,610

[52] US. Cl 128/595, 128/90, 264/45, 264/222, 264/D1G. 30 [51] Int. Cl.A4 5/14 [58] Field of Search 128/595, 594, 90, 128/89; 264/45, 222, DIG.30

[56] References Cited UNlTED STATES PATENTS 3,373,741 3/1968 Hill et a1.128/90 3,375,822 4/1968 Rose 128/90 3,674,021 7/1972 Snyder 128/903,048,169 8/1962 Pierce 128/90 2,119,590 6/1938 MacDonald 128/5952,952,082 9/1960 Murray 128/595 3,121,430 2/1964 O'Reilly 128/5953,325,919 6/1967 Robinson 128/595 X 3,407,406 10/1968 Werner et al128/595 X 3,631,854 l/l972 Fryer 128/90 3,585,639 6/1971 Enicks 128/90 X3,293,663 12/1966 Cronin 3/36 3,067,431 12/1962 Kausch 1 3/36 PrimaryExaminer-Richard A. Gaudet Assistant Examiner-J. Yasko Att0rneyArnold B.Christen et al.

57 ABSTRACT A support for the metatarsal arch of the foot is formed byinjection of a self-curing non-foamable fluid material into the archsupport enclosure. This fluid material automatically cures into a rigidsupport or prosthesis for the arch of the foot. This polymerizable material is normally contained in either a insert under the foot or by aballoon like material, in either case the polymerizable material ispumped or injected into the resulting enclosure. The same method can beused to form in situ prosthesis casts for any part of the body, i.e., toform splints, braces, etc., contured directly to the portion of thehuman body for which it is designed to lend support. The self-curingmaterial is preferably a cross-linkable prepolymerized material whichincludes an initiator, and the self-curing is achieved by theapplication of mild temperatures, e.g., 120 F.

14 Claims, 5 Drawing Figures POLYMERIZABLE MATERIAL PATENTEDJAN H9143.782.390

POLYMERIZABLE MATERIAL INVENTOR L /4C H65 AMOS N. JOHNSON me y N. M

ATTORNEY PEDICURE PROSTHESIS FOR THE METATARSAL ARCH OF THE FOOT PRIORART Foamed thermoplastic material used as prosthesis are known.

US. Pat. No. 3,257,742 shows a soft, readily deformable foot support forshoes. The support has a plastic or puttylike consistency and is a footsupport that is readily impressionable in response to pressure exertedthereon by the foot. After the foot pressure is removed, the supportreturns to its original shape. The support is essentially a cured epoxyresin or linear polybutadiene that has these characteristics, and anouter encompassing layer, such as leather, at col. 3, lines 73-74, theuncured resins are stated to be flowable so that they take the shape ofthe container into which they are poured. This patent does not disclosein situ curing in a shoe to set up a permanent foot support that istailor molded in effect to aid each foot problem. The patent furtherdiscloses the use of a hard non-foamed prosthesis.

Likewise with US. Pat. No. 3,402,41 l which is drawn to a ski-boot anklesupport and the use of polymers which lend themselves to ready moldingwhen pressure is applied with slow shape recovery.

US. Pat. No. 3,407,406 is directed essentially to a ski-boot and it usesa flexible, hollow material filled with a substance which holds itsshape a long time or until an outside pressure is exerted. The patentdoes not disclose a non-foamable, rigid, non-deformable prosthesis whichis prepared from a self-curing polymerizable material.

BROAD DESCRIPTION OF THE INVENTION The invention involves a process forpreparing a prosthesis for supporting or restraining a part of the body.The process, broadly involves placing a prosthesis enclosure on theaffected portion of the body; placing a fluid, self-curing non-foamablematerial in the prosthesis enclosure; and permitting the fluidselfcuring material to cure in situ to form a rigid cured non-foamedmaterial which conforms to the shape of the affected portion of thebody. The most preferred fluid self-curing material ispolymethylmethacrylate dissolved in monomeric methyl methylacrylate(-11] weight ratio), and the material contains about 0.1 percent ofacetyl peroxide as a catalyst (initiator).

In one embodiment, the prosthesis enclosure is first placed in a shoe,wherein the affected part of the body is the metatarsal arch of a footand wherein the prosthesis enclosure is placed on the affected portionof the body by placing the foot in the shoe. Preferably, pressure isplaced on or applied to the fluid self-curing material before itcompletely cures so that the fluid selfcuring material takes the shapeof the metatarsal arch. The pressure can be applied by the weight of thebody being shifted onto the foot. One sub-embodiment involves aprosthesis enclosure which is a sealed envelope with at least its topsurface being elastic. In this subembodiment the fluid self-curingmaterial is placed in the prosthesis enclosure by piercing a side of theprosthesis enclosure with an elongated hollow tube device and forceinjecting the fluid self-curing material through the elongated hollowtube device into the prosthesis enclosure. The hollow tube device isremoved after the fluid self-curing material is placed in the prosthesisenclosure and the side of the prosthesis enclosure is rapidly sealed.Preferably the region of the side of the prosthesis enclosure, which ispierced by the hollow tube device, is self-sealing when the hollow tubedevice is removed.

In another sub-embodiment, the preferred embodiment of the invention,the prosthesis enclosure is a rigid insert that is placed on or affixedto the insole of the shoe. The insert com'rises: a flat plate thatextends across the width of the insole and extends lengthwise at leastacross the metatrasal arch of the foot; a low side wall on the side awayfrom the metatarsal arch; and a high side wall which completely coversthe arch when the foot is inserted into the shoe. The foot serves as thetop of the prosthesis enclosure. The fluid self-curing material isplaced in the prosthesis enclosure by means of a tube inserted betweenthe high side wall and the foot. The tube is rapidly removed after thefluid selfcuring material is placed in the prosthesis enclosure.

In still another sub-embodiment of the invention, a cast is placed overthe prosthesis enclosure before the fluid self-curing material is placedin the prosthesis enclosure. This sub-embodiment can be used whenever acast is used, for example, with broken limbs.

The invention also involves the prosthesis for supporting or restraininga part of the body. The prosthesis includes a prosthesis enclosure onthe affected part of the body and a rigid, polymerized, non-foamedmaterial, within the prostheiss enclosure, which conforms to the shapeof the effected portion of the body. The prosthesis can be one where theprosthesis enclosure is located between the affected part of the bodyand a cast. The prosthesis can be one where the prosthesis enclosure islocated on the insole of a shoe where the metatarsal arch of a foot islocated. This latter prosthesis can be one where the prosthesisenclosure is a sealed enclosure. Or, preferably, this latter prosthesiscan be one where the prosthesis enclosure is a rigid insert that isplaced on or affixed to the insole of the shoe. The insert comprises: aflat plate that extends across the width of the insole and extendslengthwise at least across the metatarsal arch of the foot; a low sidewall on the side away from the metatarsal arch; and a high side wall onthe side of the metatarsal arch which completely covers the arch whenthe foot is inserted in the shoe. The foot serves as the top of theprosthesis enclosure.

DETAILED DESCRIPTION OF THE INVENTION The objects and advantages of theinvention become apparent to those ordinarily skilled in the art in thefollowing description of the invention as illustrated in theaccompanying drawing, in which;

FIG. 1 is a top view of the prosthesis of this invention;

FIG. 2 is a cross sectional view of one embodiment of preparing theprosthesis;

FIG. 3 is a partial perspective view of another embodiment of thisinvention, namely, the balloon-like enclosure;

FIG. 4 is a partial perspective view illustrating the injection of thepolymerized material into the balloonlike enclosure; and

FIG. '5 is a partial perspective view illustrating the preparation of aprosthesis which in effect is an arm cast.

FIG. 1 illustrates a rigid non-foamed arch support 4 and the transverseor metatarsal arch of the foot. FIG. 2 illustrates the embodiment of theinvention where the prosthesis is produced in situ. Foot 8 is insertedinto shoe 12. Shoe 12 contains prosthesis enclosure 16 which consists ofbase plate 20, side plates 24 and 28. Prosthesis enclosure 16 fits intothe bottom of shoe 12 so that when foot 8 is inserted into shoe 12 themetatarsal arch is completely enclosed by prosthesis enclosure 16. Baseplate must be wide enough and long enough so that the circumferenceareas of the arch are in contact therewith so that a seal is formedbetween foot 8 and base plate 20. The bottom surface of base plate 20can contain an adhesive to allow prosthesis enclosure 16 to adhere tothe inner sole and remain in the desired position. Side plate 28 islocated on the outer extermity on the foot, forming a seal by contactingthe side surface of the sole. Side wall 24 is located at the innerextremity of the foot, contacts the side of the foot, and is so shapedas to form a seal with the side of the foot. Self curing material 32 isinjected into the area enclosed by prosthesis enclosure 20 and foot 8.Material 32 is injected by means of tube 36, the tip of which isinserted into the enclosure between side wall 24 and foot 8 as shown inFIG. 2. Material 32 is pumped into the enclosure between foot 8 andpiece 16 as shown in FIG. 2. The entire enclosure is filled up withmaterial 32 and the tip of tube 36 is removed. Material 32 is then selfpolymerizable, forming in situ a non-foamable rigid prosthesis whichconforms to the metatarsal arch and gives excellant support thereof. Theform and shape of the metatarsal arch support prosthesis is determinedby the contours of the foot of the wearer who is exerting pressure onthe prosthesis as, or immediately after, the self-curing fluid system isinjected (before complete curing).

Another embodiment of the invention is illustrated in FIGS. 3 and 4.Prosthesis enclosure 40 is illustrated in a deflated condition in FIG.3. Prosthesis enclosure 40 is a completely sealed unit and is placed inthe shoe in a manner so that it is under the entire metatarsal arch andsurrounding foot portion. Enclosure 40 is made of a deformable materialat least part of which is selfsealing after puncture by a sharp object.Any selfsealing material may be used which is compatable with the footand the self-curing material. While the selfsealing portion ispreferred, the puncture area can be sealed by known methods such asthose given in US Pat. Nos. 2,646,707 and 2,803,284 which provide meansfor injecting self-curing material 44 into the internal space ofenclosure 40 by means of a hollow sharp pointed instrument 48. Any sharphollow pointed instrument, such as, a hypodermic needle, can be used forpuncturing enclosure 40 and force injecting selfcuring material 44 intothe internal space of enclosure 40 so that it may cure to form a rigidnon-foamable prosthesis. The bottom surface of the arch supportprosthesis may be coated with an adhesive to allow the device to beattached to the inner sole securely enough to remain in the desiredposition in the footwear.

FIG. 5 illustrates the universality of using this invention to form arigid supporting conformed nonfoamable prosthesis whereever any cast orsimilar enclosure is used on a human or animal. FIG. 5 specificallyillustrates the use of the prosthesis in conjunction with cast 52 onlimb 56. Cast 52 can be made of any conventional cast material, such as,plaster of Paris, or can be a relatively deformable or elastic material,such as, rubber. Between limb 56 and cast material 52, a prosthesisenclosure such as 40 in FIG. 3 is inserted and encompasses all or partof limb to illustrate this variation of this invention. Prosthesisenclosure 60 can be elongated and wrapped around limb 56 before cast 52is applied or it can be doughnut shaped and inserted over limb 56 beforecase 52 is applied. The self-curing material is injected into prosthesisenclosure 60 by means of a hypodermic needle 64. Cast 52, when it isrelatively elastic or when it is rigid, acts in effect as a restrainingforce which causes the formed prosthesis to conform to the outline ofthe limb. Thus, if the limb has been broken, it is in effect a castwhich is superior to any known cast. The self-curing material which isused to form the prosthesis should broadly be a thermal plastic materialwhich polymerized or cures in situ after being placed in the prosthesisenclosure, should not give off any gas during curing, should be gaseousor liquid, should have the same volume in the prepolymerized states asin the resulting polymerized state (i.e., as after curing), and whichshould be nontoxic or nonharmful to human or animals, particularly theeffected skin area. The term self-curing material encompasses anadmixture of any cross-linkable prepolymerized material and anyethylenically unsaturated monomer which do not cure to any substantialdegree until the admixture is placed in the prosthesis enclosure. Thisencompasses curable systems which are admixed with a catalyst andimmediately injected into the prosthesis enclosure.

The cross-linkable prepolymerized materials are broadly unsaturatedpolymerizable materials which are generally conventional classes ofknown resisn such as unsaturated polyester resins.

The preferred cross-linkable prepolymerized materials are thepoly(esters of methacrylate), and the preferred poly(ester ofmethacrylate) is poly(methyl methacrylate).

Any of the ethylenically unsaturated monomers listed below [(1) to (6)]can be prepolymerized to be used as the cross-linkable material.

The most preferred polyester resins are prepared by the esterificationof alpha, beta-unsaturated polybasic acids, (preferably a dibasic acid)and a polyhydric alcohol (preferably a dihydric alcohols). Certaincompounds of this type may be indicated generically as follows:-M-G-M-G-M-G, where -M- represents an unsaturated dibasic acid residueand -G- represents a dihydric alcohol residue. Modifying saturateddibasic acids may also be used in the polyester resin compositions.Representative dihydric alcohol and unsaturated polybasic acids areshown below.

In preparing unsaturated polyester which may be employed in the practiceof the present invention, the alcohol component may comprise one of thegroup of solid polyethylene glycols designated as Carbowax. Polyethyleneglycols such as the Carbowaxes are understood to have molecular weightsabove 300. Those most useful for this invention have weights below 4,000and preferably are in a range of about 1,000 to 2,000, e.g., 1,500.

Examples of dihydric alcohols are propylene glycol, ethylene glycol,trimethylene glycol, 2,2-dimethylpropanediol, 1,2-butanediol,ZB-butanediol, 1,3- butanediol, 1,4-butanediol, 1,5-pentanediol,3-methyll,3-butan ediol, pinacol, 2-methyl-2,4-pentanediol, 1,5-hexanediol, 1,8-heptanediol, 1,8-octanediol, 1,9- nonanediol.1,10-decanediol. 1,1 l-hendecanediol, l ,12-dodecanediol, l l3-tridecanediol, l ,14- tetradecanediol. 1,15-pentacanediol, 1,16-

hexadecanediol, 1 ,1 8-octadecanediol, 1 ,24- tetracosane and1,30-tricacontanediol. Examples of trihydric alcohols are glycerol,1,2,3-butantriol and 1,1 ,l-trihydroxymethylethane. Examples of higherpolyhydric alcohols are 1-1 ,2,3 ,4-butanetetrol,tetrahydroxyneopentane, D-arabitol, adonitol, L-arabitol, xylitol,sorbitol, D-mannitol, o-iditol, dulcutol, L-tatitol, styracitol,perseitol, volemitol, cellobiitol, lactitol, melibiitol, maltitol.

The acid component usually comprises an alpha, beta-ethylenicallyunsaturated polycarboxylic acid such as maleic, fumaric or itaconicacid, or the wellknown derivatives of these polycarboxylic acids havingethylenic unsaturation in alpha-beta relation to the carboxyl group.Polybasic acids such as aconitric acid, tricarballylic acid or citricand may also be employed. A plurality of such acids may also be mixedwith each other, if so desired. In many instances, it may be desirableto include a dicarboxylic acid free of ethylenic unsaturation. Examplesof this latter type of dicarboxylic acid include phthalic acid orterephthalic acid, which although they contain double bonds in thebenzene ring, do not undergo addition reaction with monomer compoundsand may, therefore be considered as being the equivalent of saturatedcompounds. Likewise, aliphatic dicarboxylic acids such as succinic acid,adipic acid, sebacic acid, or azelaic acid, may be substituted for apart of the alpha, beta-ethylenically unsaturated dicarboxylic acid. Theproportion of the non-ethylene acid with respect to the alpha,betaethylenically unsaturated acid is susceptible of wide variation. Amolecular proportion of 0.25 to 12 moles of saturated acid per mole ofunsaturated acid is usually used for commercial applications. Also acidanhydrides of these dicarboxylic acids can be used instead of thedicarboxylic acids.-

The cross-linked prepolymerized materials can be prepared by anyconventional method. In preparing a polyester, a small excess (usuallyfive or percent) of the dihydric alcohol is usually employed. Theconditions of the esterification reaction are those conventionallyemployed in preparing polyesters. For example, the mixture of thealcohol and the acid is heated in a vented container or under an inertatmosphere until the water of reaction is expelled from the system,which usually occurs in a temperature range of about 150 to 210 C. Thereaction is continued until the acid value is reduced to a reasonablelow point, e.g., within a range of about five to 50, or until themixture becomes highly viscous or even solid when it is cooled. Usuallythese conditions are attained in a period of 2 to hours. in the eventthe reaction is concluded before the product becomes infusible andinsoluble because of the advanced stage of polymerization. The productis then blended with the ethylenically unsaturated monomer in such amanner as to maintain the temperature of the blend below 150 F.

The preferred ethylenically unsaturated monomers which can be used asthe cross-linking agent are the esters of methyacrylate and the mostpreferred is methyl methacrylate.

The ethylenically unsaturated monomers which can be used as thecross-linking agent may be selected from the following general list:

l. Monoolefinic hydrocarbons, that is, monomers containing only atoms ofhydrogen and carbon, such as styrene, alpha-methyl styrene, alpha-ethylstyrene, alpha-butyl styrene, vinyl toluene and the like;

2. Halogenated monoolefinic hydrocarbons, that is, monomers containingcarbon, hydrogen and one or more halogen atoms such asalpha-chlorostyrene, alpha-bromo-styrene, 2,5-dichlorostyrene., 2,5-dibromostyrene, 3 ,4-dichlorostyrene, 3 ,4- difluorostyrene, ortho-,meta and parafluorostyrenes, 2,6-dichlorostyrene, 2,6-difluorostyrene,3-fluoro-4- chlorostyrene, 2,4,5-trichlorostyrene,dichloromonofluorostyrene, chloroethylene (vinyl chloride), 1,1-dichloroethylene (vinylidene chloride), bromoethylene, fluorethylene,iodoethylene, 1 ,1 dibromoethylene, 1,1-difluoroethylene, 1 ,1-diiodoethylene and the like;

3. Esters of organic and inorganic acids such as vinyl acetate, vinylpropionate, vinyl butyrate, vinyl isobutyrate, vinyl avalerate, vinylcaproate, cinyl enanthate, vinyl benzoate, vinyl toluate, vinylp-chlorobenzoate, vinyl o-chlorobenzoate, vinyl m-chlorobenzoate, andsimilar vinyl halobenzoates, vinyl p-methoxybenzoate, vinylo-methoxybenzoate, vinyl p-ethoxybenzoate, methyl methacrylate, ethylmethacrylate, propyl methacrylate, butyl methacrylate, amylmethacrylate, hexyl methacrylate, heptyl methacrylate, octylmethacrylate, decyl methacrylate, methyl crotonate, ethyl crotonate, andethyl tiglate, methyl acrylate, ethyl acrylate, propyl acrylate,isopropyl acrylate, butyl acrylate, isobutyl acrylate, amyl acrylate,hexyl acrylate, Z-ethylhexyl acrylate, heptyl acrylate, octyl acrylate,1,5, 5- trimethylhexyl acrylate, decyl acrylate, and dodecyl acrylate,isopropenyl acetate, isopropenyl priopionate, isopropenyl butyrate,isopropenyl valerate, isopropenyl caproate, isopropenyl enanthate,isopropenyl benzoate, isopropenyl p-chlorobenzoate, isopropenylobromobenzoate, isopropenyl m-chlorobenzoate, isopropenyl toluene,isopropenyl alpha-chloracetate and isopropenyl alpha-bromopropionate;

Vinyl alpha-chloroacetate, vinyl alphabromoacetate, vinylalpha-chloropropionate, vinyl alpha-bromopropionate, vinylalpha-iodopropionate, vinyl alpha-chlorobutyrate, vinylalpha-chlorovalerate and vinyl alpha-bromovalerate;

Allyl chlorocarbonate, allyl formate, allyl acetate, allyl propionate,allyl butyrate, allyl valerate, allyl caproate, diallyl phthalate,diallyl succinate, diethylene t s(allylrb ly! l5-t i hy hezt9- ate,allyl benzoate, allyl acrylate, allyl crotonate, allyl oleate, allylchloroacetate, allyl trichloroacetate, allyl chloropropionate, allylchlorovalerate, allyl lactate, allyl pyruvate, allyl aminoacetate, allylaminoacetate, allyl acetoacetate, allyl thioacetate, diallyl-3,4,5,6,7,--i -wmc ll qns tst r gh ha as well as methallyl esters corresponding tothe above allyl esters, as well as esters from such alkenyl alcohols asbeta-ethyl allyl alcohol, beta-propyl allyl alcohol, 1- buten-4-ol,2-methyl-buten-1-01-4, 2(2,2-dimethyl propyl -l-buten-4-ol and lpentene-4-ol; m

Methyl alpha-chloroacrylate, methyl alphabromoacrylate,methyl-alpha-fluoroacrylate, methyl alpha-iodoacrylate, ethylalpha-chloroacrylate, propyl alpha-chloroacrylate, isopropylalpha-bromoacrylate, amyl alpha-chloroacrylate, oc'tylalphachloroacrylate, ,5. i imethy hsma kfiama uvets? chloroacrylate,methyl alpha-cyano acrylate, ethyl alpha-cyano acrylate, amylalpha-cyano acrylate, amyl alpha-cyano acrylate and decyl alpha-cyanoacrylate;

Dimethyl maleate, diethyl maleate, diallyl maleate, dimethyl fumarate,dimethallyl fumarate and diethyl glutaconate;

4. Organic nitriles such as acrylonitrile, methacrylonitrile,ethacrylonitrile, crotonitrile, and the like;

5. Acid monomers such as acrylic acid, methacrylic acid, crotonic acid,3-butenoic acid, angelic acid, tiglic acid and the like; 7 W V 6. Amidessuch acrylamide, alpha-methyl acrylamide, N-phenyl acrylamide,N-methyl-N-phenyl acrylamide, N-methyl acrylamide, and the like.

The total mols of acid constituents of the unsaturated polybasic acid(and any saturated polybasic acid) are preferably balancedstoichiometrically with the polyfunctional alcohol.

Because of the mature of the invention, the preferred monomers areliquid compounds soluble in the crosslinkage prepolymerized material.This means that the cross-linked prepolymerized material is ahomopolymer and the monomer is the same monomer from which thecross-linkable prepolymerized material is formed, because the liquidmonomer is then most likely soluble in the prepolymerized material andvice versa Solvents can be used, but very little if any solvent shouldbe used because of the enclosed curing (crosslinking) area used in thisinvention. Examples of useful solvents and diluents are: alcohols, suchas, methanol (b.p. 64 C.), ethanol (b.p. 78 C), isopropanol (b.p. 80C.), propanol (b.p. 95 C.), N-butyl alcohol (b.p. 118 C.), secondarybutyl alcohol (b.p. 99 C.), isobutyl alcohol (b.p. 107 C.), and methylisobutyl carbinol (b.p. 131 C.), glycol ethers, such as, ethylene glycolmonomethyl ether (b.p. 125 C.), ethylene glycol monoethyl ether (b.p.136 C.), ethylene glycol monobutyl ether (b.p. 171 C.), diethyleneglycol monomethyl ether (b.p. 194 C.), diethylene glycol monoethyl ether(b.p. 195 C.) and diethylene glycol monobutyl ether (b.p. 230 C.);ketones such as, acetone (b.p. 56 C.), methyl ethyl ketone (b.p. 79 C.methyl isobutyl ketone (b.p. 115 C.) and isophones (b.p. 207 C.);aliphatic hydrocarbons, such as hexane, (b.p. 155 C.) and heptane (b.p.201 C. esters such as, ethyl acetate, amyl acetate and butyl acetate;aromatic hydrocarbons such as benzene (b.p. 80 C.), toluene (b.p. 110C.) and mixed xylene (b.p. 275 C.); and halogenated hydrocarbons suchas, chloroform, perchloroethylene, carbon tetrachloride (b.p. 76 C.) andtrichloroethylene (b.p. 86 C Water, and water plus another dilutent(water is usually not a solvent for organic materials) can be used, butneither is preferred. A dilutent means that the carrier is not a solventfor the polymeric constituents, catalyst, etc., being used.

In general, the monomer component or components may be employed over arelatively broad range, but usually, the amount thereof upon a weightbasis will be less than that of the prepolymerized material. Usually,the percentage of monomer will fall within a range of about to 45percent by weight of the total mixture of the prepolymerized materialand monomer. The preferred range of monomer is about 20 to 40 percent inmost instances.

The curing time of the systems varies between about 1 minute and about24 hours. This time span depends, in part, upon the type ofprepolymerized material, the monomer, the amount of catalyst, the amountof inhibitor, and so forth. The curing temperature of the resin systemsvaries, and preferably the resin system can be cured at room temperature(15 to 30 C.).

The curing temperature should not be so high that the wearer cannot keephis foot, etc., in the shoe when the rigid form of the prothesis isbeing prepared by the curing. Also the curing time should be two hoursor less for the comfort of the wearer.

As the scope of useful resin systems is extensive, the type of promotorwhich can be used in those systems is also extensive. A few exemplarypromotors are given in the following paragraphs.

One of the promotor types which can be used in the resin system is acobalt salt which is capable of being dissolved in the resinouscomposition. Suitable soluble promoters are cobalt octoate or any otherhigher fatty acid salt of cobalt. The amount of cobalt salt can bevaried from about 0.001 to 0.3 percent of the salt calculated asdissolved metallic cobalt based on the total weight of the resincompounds, catalysts and promoter mixture employed. On the same basis,the preferred amount of cobalt metal ranges from about 0.05 to 0.15percent.

The vanadium promoters disclosed in U.S. Pat. No. 3,333,021 are useful.

Another promotor type material is a variety of amine promoters. Suitableamine promoters are disclosed in U.S. Pat. No. 2,480,928. The promotersare described therein as tertiary monoamines which contain attached tothe nitrogen atom two functionally aliphatic radicals selected from thegroup consisting of alkyl hydrocarbons, hydroxy-substituted alkylhydrocarbons and aralkyl hydrocarbons and one aromatic radical selectedfrom the group consisting of aryl hydrocarbons, azosubstituted arylhydrocarbons, amino-substituted aryl hydrocarbons and salts thereof.Specific examples of thisclass are the following: dimethylaniline,diethylaniline, di-n-propyaniline, dimethyl-p-toluidine,dimethyl-o-toluidine,dimethyl alpha-naphthylamine, methyl benzylaniline, p-dimethylamino-azobenzene, N,N-di-methyl-m-aminophenol,pdimethylaminophenyl oxalate, dimethylaminobenzaldehyde,p-dimethylaminophenyl acetate, and p-hydroxy-N,N-di(beta hydroxyethyl)aniline. Additionally, the promotor can be a tertiary alkyl amine, ahydroxy alkyl amine or an acid salt thereof as a promoter. Examplary ofthese types of promoters are diethylmethylolamine, triethylamine,triisopropylamine, trimethylamine, triisopropanolamine, ethyldiethanolamine hydrochloride and the like. Tertiary polyamines are alsoeffective for use in the instant manner, such as for example,tetramethylbutanediamine. The amount of amine promoter useful in thepractice of this invention varies between about 0.05 to 1.0 percentbased on the resin components, catalyst and promoter. These aminepromoters can be used in conjunction with the above cobalt promoters.

The resin systems of this invention (containing the monomer and theprepolymerized material) are readily cured by any conventional catalyst.The preferred catalysts are organic peroxides most preferably diocylperoxides, and the preferred organic peroxide is acetyl peroxide.Examples of other useful diacyl peroxides are caprylyl peroxide, lauroylperoxide, decanoyl peroxide, 2,4-dichlorobenzol peroxide,p-chlorobenzoylperoxide, pelargonyl peroxide and propionyl peroxide. Other usefulorganic peroxide catalysts include: peroxyesters, such as, tert.-butylperoxyacetate, tert.buty1 peroxyisobutyrate, tert.-butyl peroxypivalate,tert.-butyl peroxybenzoate, tert.- butyl peroxy (2- ethylhexanoate),2,5-dimethyl-2,5-bis- (benzoylperoxy) hexane, 2 ,5 -dimethylhexane-2 ,5-

diperoctoate, and di-tert.-butyl diperoxyphthalate; alkyl peroxides,such as, di'tert. butyl peroxide, nbutyl-4,4-bis(tert.-butylperoxy)valerate,2,S-dimethyl- 2,5-bis (tert.-butylp eroxy) and 2,5-dimethyl2,5-bis (tert.-butylperoxy) hexyne-3; hydroperoxides, such as,tert.-butyl hydroperoxide, a-cumyl hydroperoxide and2,5-dimethylhexane-2,S-dih ydroperoxide; and ketone peroxides, such as,methyl ethyl ketone peroxides, cyclohexane peroxides and bis(l-hydroxyclohexyl) peroxide.

Preferably the catalyst is used in an amount small enough to get a fastcure without excessive heat production. Usually from 0.01 to 2 percentof catalyst, based on the total weight of the resin components, areused. Preferably about 0.1 percent of catalyst is used.

The resin systems of this invention can also contain other compatibleadditives, such as, dyes, reinforcing materials (asbestos, chopped glassfibers), etc. The fluid polymerizable composition can also containcompatible plasticizers, such as, di-n-butyl styryl phosphonate anddimethyl phthalate; and compatible fillers, such as, silicon dioxide,titanium dioxide, calcium carbonate, silica and carbon black. The fluidpolymerizable composition can also contain a compatible conventionalinhibitor.

To add structural body to the cured polymer resins, materials, such asstyrene, vinyl toluene, a-methylstyrene, dimethylstyrene, themethyl-a-methylstyrenes, a-bromostryene, B-bromostyrene,a-chlorostyrene, B-chlorostyrene, diallyphthalate, vinyl acetate, methylmethacrylate and divinylbenzene, can be added to the uncured polymerresins so that they can be copolymerized with the other monomercomponents.

The systems of this invention can be stored for long times, eitherseparately or mixed (provided in the latter instance a catalystedmixture must be heated to initiate the curing to any significantdegree).

' The surface of any prosthesis can be covered with a soft flexiblematerial which makes it soft and comfortable to the skin. For example,the top of a foot prosthesis may be covered with leather, or simulatedleather. The surface of the prosthesis not contacting the skin may beadhered, for example, by gluing, to the cast or shoe to insure theprosthesis remains securely in the desired position in relationship tothe cast or footwear and the body part.

A package to be purchased by the shoe wearer could contain oneprosthesis for each foot, the injection devices and material to beinjected, and detailed instructions for the mechanism to be utilized inthe injection of the thermoplastic fluid into the hollow interior of theprosthesis. The actual injection of the materials into the cavity of thearch support could be done as a skilled service by the trained footwearsalesman or could be done by the purchaser of the articles of footwear.First aid kits or hospital kits could be similarly packaged and sold foruse when casts are applied.

1.0 mole percent is 0.01 mole per 100 grams of resin. Weight percent orpercent by weight as used throughout this application, unless otherwisespecifically stated, is defined conventionally as grams per 100 grams ofresin.

The following examples illustrate this invention. All percentages andparts therein are by weight, unless otherwise stated.

EXAMPLE A foot was placed in a show as shown in FIG. ii, the prosthesisenclosure 16 being made of aluminum. Poly( methyl methacrylate) wasdissolved in monomeric methyl methacrylate in a ratio of 1:1 by weight.The solution was then admixed with 0.1 percent by weight, based on thatcomposition, of acetyl peroxide an initiator. The catalyzed solution wasinjected into the enclosed area by means of line 36. Line 36 wasremoved. The catalyzed solution rapidly polymerized at F. and wasallowed to self cure to a rigid prosthesis for the metatarsal arch ofthe foot. A leather covering was placed between the prosthesis and thefoot.

What is claimed is:

1. The process for preparing a prosthesis for supporting or restraininga part of the body which comprises: (a) placing a fluid, self-curing,non-foamable material in said prosthesis enclosure, said fluidself-curable material being comprised of an admixture of a crosslinkableprepolymerized material, which is a poly(ester of methacrylate), and anethylenically unsaturated monomer, which is an ester of methacrylate,and (b) permitting said fluid self-curing material to cure in situ at atemperature between 59 and 120 F. to form a rigid cured material whichconforms to the shape of the affected portion of the body and which hasessentially the same volume in the pre-cured state as in the curedstate, there being no gas given off during the curing.

2. The process of claim 1 wherein said prosthesis enclosure is firstplaced in a shoe, wherein said affected part of the body is themetatarsal arch of a foot, and wherein said prosthesis enclosure isplaced on the affected portion of said body by placing said foot in saidshoe.

3. The process of claim 2 wherein pressure is placed on said fluidself-curing material before it completely cures so that said fluidself-curing material takes the shape of said metatarsal arch.

4. The process of claim 2 wherein said fluid selfcuring material iscomprised of poly(methyl methacrylate), monomeric methyl methacrylateand acetyl peroxide.

5. The process of claim 2 wherein said prosthesis enclosure is a sealedenvelope, with at least its top surface being elastic, wherein saidfluid self-curing material is placed in said prosthesis enclosure bypiercing a side of said prosthesis enclosure with an elongated, hollowtube device and force injecting said fluid self-curing material throughsaid elongated, hollow tube device into said prosthesis enclosure, andwherein said hollow tube device is removed from said fluid self-curingprosthesis enclosure and said side of said prosthesis enclosure israpidaly sealed.

6. The process of claim 5 wherein said region of said side of saidprosthesis enclosure which is pierced by said hollow'tube device isself-curing.

7. The process of claim 3 wherein said prosthesis enclosure is a rigidinsert that is placed on or affixed to the insole of said shoe, saidinsert comprising a flat plate that extends across the width of saidinsole and extends lengthwise at least across the metatarsal arch ofsaid foot, and a low side wall on the side away from said metatarsalarch which completely covers said arch when said foot is inserted insaid shoe, said foot serving as the top of said prosthesis enclosure,wherein said fluid self-curing material is placed in said prosthesisenclosure by means of a tube inserted between said high side wall andsaid foot, and wherein said tube is rapidly removed after said fluidself-curing material is placed in said prosthesis enclosure.

8. The process of claim 2 wherein a cast is placed over said prosthesisenclosure before said fluid selfcuring material is placed in saidprosthesis enclosure.

9. The prosthesis for supporting or restraining a part of the body whichcomprises a prosthesis enclosure and a rigid, cured non-foamed material,within the prosthesis enclosure, with conforms to the desired shape andwhich has essentially the same volume in the cured state as it had inthe pre-cured state, said rigid, cured, non-foamed material comprising aprepolymerized material, which is a poly(ester of methacrylate),crosslinked by an ethylenically unsaturated monomer, which is an esterof methacrylate, said rigid, cured nonfoamed material having been curedat a temperature between 59 and F.

10. The prosthesis of claim 9 wherein said prosthesis enclosure islocated between said affected part of the body and a cast.

11. The prosthesis of claim 10 wherein said prosthesis enclosure islocated on the insole of a shoe where the metatarsal arch of a foot islocated.

12. The prosthesis of claim 11 wherein said prosthesis enclosure is asealed enclosure.

13. The prosthesis of claim 12 wherein said prosthesis enclosure is arigid insert that is placed on or affixed to said insole of said shoe,said insert comprising a flat plate that extends lengthwise across thewidth of said insole and extends lengthwise at least across themetatarsol arch of said foot, and a low side wall on the side away fromsaid metatarsal arch which completely covers said arch when said foot isinserted in said shoe, said foot serving as the top of said prosthesisenclosure.

14. The prosthesis of claim 13 wherein said prosthesis enclosure iscomprised of aluminum.

1. The process for preparing a prosthesis for supporting or restraininga part of the body which comprises: (a) placing a fluid, self-curing,non-foamable material in said prosthesis enclosure, said fluidself-curable material being comprised of an admixture of across-linkable prepolymerized material, which is a poly(ester ofmethacrylate), and an ethylenically unsaturated monomer, which is anester of methacrylate, and (b) permitting said fluid self-curingmaterial to cure in situ at a temperature between 59* and 120* F. toform a rigid cured material which conforms to the shape of the affectedportion of the body and which has essentially the same volume in thepre-cured state as in the cured state, there being no gas given offduring the curing.
 2. The process of claim 1 wherein said prosthesisenclosure is first placed in a shoe, wherein said affected part of thebody is the metatarsal arch of a foot, and wherein said prosthesisenclosure is placed on the affected portion of said body by placing saidfoot in said shoe.
 3. The process of claim 2 wherein pressure is placedon said fluid self-curing material before it completely cures so thatsaid fluid self-curing material takes the shape of said metatarsal arch.4. The process of claim 2 wherein said fluid self-curing material iscomprised of poly(methyl methacrylate), monomeric methyl methacrylateand acetyl peroxide.
 5. The process of claim 2 wherein said prosthesisenclosure is a sealed envelope, with at least its top surface beingelastic, wherein said fluid self-curing material is placed in saidprosthesis enclosure by piercing a side of said prosthesis enclosurewith an elongated, hollow tube device and force injecting said fluidself-curing material through said elongated, hollow tube device intosaid prosthesis encLosure, and wherein said hollow tube device isremoved from said fluid self-curing prosthesis enclosure and said sideof said prosthesis enclosure is rapidaly sealed.
 6. The process of claim5 wherein said region of said side of said prosthesis enclosure which ispierced by said hollow tube device is self-curing.
 7. The process ofclaim 3 wherein said prosthesis enclosure is a rigid insert that isplaced on or affixed to the insole of said shoe, said insert comprisinga flat plate that extends across the width of said insole and extendslengthwise at least across the metatarsal arch of said foot, and a lowside wall on the side away from said metatarsal arch which completelycovers said arch when said foot is inserted in said shoe, said footserving as the top of said prosthesis enclosure, wherein said fluidself-curing material is placed in said prosthesis enclosure by means ofa tube inserted between said high side wall and said foot, and whereinsaid tube is rapidly removed after said fluid self-curing material isplaced in said prosthesis enclosure.
 8. The process of claim 2 wherein acast is placed over said prosthesis enclosure before said fluidself-curing material is placed in said prosthesis enclosure.
 9. Theprosthesis for supporting or restraining a part of the body whichcomprises a prosthesis enclosure and a rigid, cured non-foamed material,within the prosthesis enclosure, which conforms to the desired shape andwhich has essentially the same volume in the cured state as it had inthe pre-cured state, said rigid, cured, non-foamed material comprising aprepolymerized material, which is a poly(ester of methacrylate),cross-linked by an ethylenically unsaturated monomer, which is an esterof methacrylate, said rigid, cured non-foamed material having been curedat a temperature between 59* and 120* F.
 10. The prosthesis of claim 9wherein said prosthesis enclosure is located between said affected partof the body and a cast.
 11. The prosthesis of claim 10 wherein saidprosthesis enclosure is located on the insole of a shoe where themetatarsal arch of a foot is located.
 12. The prosthesis of claim 11wherein said prosthesis enclosure is a sealed enclosure.
 13. Theprosthesis of claim 12 wherein said prosthesis enclosure is a rigidinsert that is placed on or affixed to said insole of said shoe, saidinsert comprising a flat plate that extends lengthwise across the widthof said insole and extends lengthwise at least across the metatarsolarch of said foot, and a low side wall on the side away from saidmetatarsal arch which completely covers said arch when said foot isinserted in said shoe, said foot serving as the top of said prosthesisenclosure.
 14. The prosthesis of claim 13 wherein said prosthesisenclosure is comprised of aluminum.